The present invention is directed to a fluid mount. More specifically, the present invention is directed to a multiple chamber fluid mount for an exposure apparatus and a method for making a multiple chamber fluid mount for dampening vibration. Additionally, the present invention is directed to an exposure apparatus having improved isolation.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an apparatus frame, a measurement system, a control system, an illumination source, an optical assembly, a reticle stage for retaining a reticle, and a wafer stage for retaining a semiconductor wafer.
The apparatus frame typically supports the measurement system, the illumination source, the reticle stage, the optical assembly, and the wafer stage above the ground. The measurement system monitors the positions of the stages relative to a reference such as the optical assembly. The optical assembly projects and/or focuses the light that passes through the reticle. One or more movers precisely position the reticle stage relative to the optical assembly. Similarly, one or more movers precisely position the wafer stage relative to the optical assembly.
The size of the images and the features within the images transferred onto the wafer from the reticle are extremely small. Accordingly, the precise positioning of the wafer and the reticle relative to the optical assembly is critical to the manufacture of high density, semiconductor wafers.
Unfortunately, mechanical vibrations and deformations in the apparatus frame of the exposure apparatus can influence the accuracy of the exposure apparatus. For example, the movers utilized to move the stages generate reaction forces that vibrate and deform the apparatus frame of the exposure apparatus. Further, the ground can transfer vibration to the apparatus frame.
The vibrations and deformations in the apparatus frame can move the stages and the optical assembly out of precise relative alignment. Further, the vibrations and deformations in the apparatus frame can cause the measurement system to improperly measure the positions of the stages relative to the optical assembly. Additionally, vibration of the optical assembly can cause deformations of the optical elements within the optical assembly and degrade the optical imaging quality. As a result thereof, the accuracy of the exposure apparatus and the quality of the integrated circuits formed on the wafer can be compromised.
One attempt to solve this problem involves the use of one or more air mounts to secure the apparatus frame to the ground. The air mounts reduce the effect of vibration of the ground causing vibration to the apparatus frame. Similarly, one or more air mounts can be used to secure the components of the exposure apparatus to the apparatus frame. Unfortunately, existing air mounts with adequate dampening capacity have a relatively large footprint. As a result thereof, the resulting exposure apparatus is larger. Further, the existing air mounts may reduce the access to the other components of the exposure apparatus.
In light of the above, there is a need for an exposure apparatus with an improved isolation system. Additionally, there is a need for a fluid mount having relatively small footprint with relatively high dampening ability. Further, there is a need for an exposure apparatus capable of manufacturing precision devices, such as high density, semiconductor wafers.
The present invention is directed to a fluid mount for an exposure apparatus that satisfies these needs. The fluid mount includes a first subsystem and a second subsystem. The first subsystem includes a first cylinder and a first piston. The first piston moves within the first cylinder along a first axis. The second subsystem includes a second cylinder and a second piston. The second piston moves within the second cylinder along a second axis.
Importantly, the second axis is substantially coaxial with the first axis. Further, the first piston and the second piston are mechanically coupled together. Moreover, the second subsystem is stacked on top of the first subsystem. As a result of this design, the fluid mount has a smaller footprint with relatively high load carrying capacity.
As provided herein, the first piston cooperates with the first cylinder to define a first chamber and the second piston cooperates with the second cylinder to define a second chamber. Further, the first chamber can be in fluid communication with the second chamber.
Additionally, the fluid mount can include a third subassembly stacked on top of the second subassembly. The third subassembly includes a third cylinder and a third piston moving within the third cylinder along a third axis. The third axis is substantially coaxial with the first axis and the second axis. In this embodiment, the first piston, the second piston and the third piston are coupled together and move concurrently. Further, each of the pistons can be connected to the load.
The present invention is particularly useful as part of an exposure apparatus. For example, one or more fluid mounts can be used as part of a frame isolation system that secures an apparatus frame of the exposure apparatus to a mounting base. With this design, the frame isolation system reduces the effect of vibration of the mounting base causing vibration on the apparatus frame and the components that are secured to the apparatus frame.
Further, one or more of the fluid mounts can be used to secure one or more subassemblies of the exposure apparatus to the apparatus frame. For example, one or more fluid mounts could be used as part of an isolation system to secure a stage subassembly or an optical subassembly to the apparatus frame. With this design, the isolation system reduces the effect of vibration of the apparatus frame causing vibration on the stage subassembly or the optical subassembly.
The present invention is also directed to a device made with the exposure apparatus, a wafer made with the exposure apparatus, a method for making a fluid mount, a method for making an isolation system, a method for making an exposure apparatus, a method for making a device, and a method for making a wafer.